Fix CDCC phase-out calculations

[martinholmer]

Fixes #2778.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 99.42%. Comparing base (e9900f2) to head (f272eee).

Additional details and impacted files

[](https://app.codecov.io/gh/PSLmodels/Tax-Calculator/pull/2779?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=PSLmodels) ```diff @@ Coverage Diff @@ ## master #2779 +/- ## ======================================= Coverage 99.42% 99.42% ======================================= Files 13 13 Lines 2610 2613 +3 ======================================= + Hits 2595 2598 +3 Misses 15 15 ``` | [Flag](https://app.codecov.io/gh/PSLmodels/Tax-Calculator/pull/2779/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=PSLmodels) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/PSLmodels/Tax-Calculator/pull/2779/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=PSLmodels) | `99.42% <100.00%> (+<0.01%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=PSLmodels#carryforward-flags-in-the-pull-request-comment) to find out more. | [Files](https://app.codecov.io/gh/PSLmodels/Tax-Calculator/pull/2779?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=PSLmodels) | Coverage Δ | | |---|---|---| | [taxcalc/taxcalcio.py](https://app.codecov.io/gh/PSLmodels/Tax-Calculator/pull/2779?src=pr&el=tree&filepath=taxcalc%2Ftaxcalcio.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=PSLmodels#diff-dGF4Y2FsYy90YXhjYWxjaW8ucHk=) | `100.00% <100.00%> (ø)` | |