Summing up the coefficients

[Padmavathi Bandaru]

Dear all,

I have panel data for all variables tariff, emissions and industry for five years. I am trying to find association of tariff and emissions. I use the following code for it.
How do I sum up the main effect of emissions and interaction terms for each year and test for its significance?

reghdfe tariff i.year##c.emissions, a(industry) cluster(industry)

Thank you

[Clyde Schechter]

levelsof year, local(years)
foreach y of local years {
    display `"Year: `y'"'
    lincom _b[emissions] + _b[`y'.year#c.emissions]
}